Apparatus for homogeneous blending



Jan. 20, 1959 J.. H. PlCKlN APPARATUS FOR HOMOGENEOUS BLENDING Filed July 15, 1956 INVENTOR (/0121; {Z Pz'afizkz ATTORNEY Unite States 2,869,837 I APPARATUS 1 FOR HOMOGENEOUS QBL'EN-DING Join ;I larlan;Pickin,lYlaglison, N. J., assignor to Colgate- Palmoliye Company, lfiewlYork, N. Y., a corporation iaDe awar Appiication luly: 13, 1956, SerialNo. 5973693 sprains.. c1. 259 -3 granular materials are blended by stirring, beating, agitatingor; rolling.

It has been found, where materials to be blendedvary in particle size and density, that in using-these conventional mixers or blenders, considerable c-are in5the blending mustbe'taken to avoid stratification of-- the like particles 7 whichjresults in a mixture lacking homogeneity.

Thisinvention contemplates: an improved" apparatus for-producing homogeneous blending of powdered and granular materi-als'varying in particle size and apparent density-by passing a continuous stream of'material. to be blerided along a spiral path around the inner surface *ofa rotating drumandeffecting alternate splitting and recombining of the material passing through the'rotat- 'ingd'rum'; The spiral'path isformed'in such atmanner around the inner surface of the drum that the material fed' into one end of" the drum is picked up by the entrance section of the spiral path and forced to travel through a series f-alternate convergentanddivergent sections throughout the length of the drum. In the spiral path formed from. a series of alternately diverging and converging walls are wedge-shaped flow splitting battles with the point ofeach wedge-shaped baflie being centered at the exit end of eachconvergent section. Thematerial isforced to pass-along-thespiral path by the rotationof the rotary-drum which inches the material forward by lifting and falling actions as the material is carried upwards against gravity by the rotation of the drum.

The continuous splitting and recombining of the material, which varies in particle size and apparent density,

atent' as it passes through the drum produces with ease and in 7 an efiicient manner a homogeneous blend heretofore found difiicult to obtain.

An object of the invention is to provide an apparatus for the continuous blending of material having different specific surfaces and apparent densities by continuous splitting and recombining of a stream of material as it travels along a spiral path in a rotary drum.

A still further object of the invention is to provide a blending apparatus having a spiral path around the inner surface of a rotary drum with alternate convergent and divergent sections forming the spiral path and having a splitting wedge located at the exit of each of the convergent sections so that a stream of material passing along the spiral path is continuously split and recombined throughout its travel.

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Additional objects will become apparent-from amexamination of the drawings,v description and claims;

The inventionrwill be 1 described further. in connection with the accompanying drawingswhich are. to ,be. considered as. an exemplification: of :the invention and do not constitute limitations thereof.

In the drawings:

Figure l is .a viewJin. perspective. showing: alrotary drum arrangement with a. spiral path. formed on; the inner surface: of: the drum, at. feeding-rchuten for feeding the materialinto the-drum; and: adischargezchute for removing the material after blending;

Figure 2' is an end; view. ofrFigurew 1- showing the convergent and divergent walls which formthe spiral path around the inner 1 surface ,of "thedrum; and

Figured ista fragmentary sectional 1 elevationaliview, alongsthe line 3-3 ofiFigure 2, showing-the-convergent andrdivergent sections :forming the spiral path with wedge.- shaped baffiesl located at the eXitof the. convergent sections for splittingsth'e flowof-material- The invention will be 'describedin detail in. connection with the.accompanying-drawings, in-whi ch Figure 1 shows a horiZontal'ro-tary. drum 10'provided" with a material feedichute l'lIWl'liCl'I supplies a: continuous stream of materialto beblendedto; the entrance sectionlZ of the drum. On theinner surface;- of the rotary drum 10. is a spiral path 13 whichtravelswaround the inner surface ofi'thedrum for its entire length. The spiral path is defined by aseries :of convergent sections .141and divergent sections. 15, which alternate throughout-the path along the; innersurfacegof the drum. The spiral path ,is form'ed from a seriesofi:angnlarly'positioned walls 16'whi'ch extend towards the. center line:- ofjth'e drum for a; distance 6611121110 aport-ion.of the-- radius. of the: drum wand are welded at their base to" the surface of the: drum. Wall ltissin portions which are. positioned in reversed angularity with respect to .each: other. The convergent and divergent sections of-the. spiral path are formed by. the angular walls 16, being so arranged that the side of one convergent section forms the side of the divergent section of: the next turn of 'the: spiral. This arrangement-of alternate divergent" and. convergent sections provides a series of convergent throats 17-for funneling the materi'al from the convergentsection into the divergent section.

Located in each divergent section 15 is'a wedge-shaped bathe TS-having. its'point 19; centered with respect to throatt17. The -wedge-shaped' bafile has faces Zlisubstantiallyv parallel tothez wall 16 of thedivergent section 1'5 and. thusdefines two channels-21 throughwhichthe materialzleaving, throati 17" must pass. The Wedge battle 18;.has-a1flatzside22 which. isi-paralleltothe axisof the rotary-drum at the end of :thea'divergent section 15.. This arrangement of alternate convergent and divergent sections with a wedge-shaped baffle positioned in the center of path 13 of each divergent section 15 provides for the funneling ot' the "material so that it can be split into two streams by the baffle as it passes through the divergent section from the convergent section and recombines in the next convergent section.

At the exit end of the rotary drum is located a receiving hood 23 into Which the blended material falls after passing along the spiral path of the rotary drum. The receiving hood terminatesin' a funnel 24 having an out let opening 25 for conveying the blended material from the blending system.

In operation, granular material to be blended is fed through chute 11 into the front end of a slowly rotating drum to. As the drum rotates, the entrance section 12 picks up the unblended material as the drum revolves around its longitudinal axis. The material forced to enter the spiral path 13 is first converged in convergent section 14 and, when leaving the section passing through throat 17, it is split'into two streams by the splitting baffle 18. The split streams pass through channels 21 and are recombined as they enter the next convergent section. Continuous splitting and recombining'of the material as it is inched alongthe spiral path of the rotating drum produces intimate mixing of the particles in the material so that stratification of like particles is prevented and a homogeneous blending of material initially varying in particle size and apparent density is produced. 7

After the material has passed along the length of the spiral in the rotary drum, it exits into a hood arrangement where the blended material is funneled to a convenient discharging device for removal from the blending system.

The movement of granular materials through the rotary drum is accomplished by presenting a continuous flight in the form of a spiral path around the inner surface of the rotating drum. As the drum rotates, the material is forced to travel in a longitudinal direction as it flows along the spiral path. The particles of the material are lifted by the rotating action of the drum until gravity causes them to slide and fall downward, thereby advancing the material along the spiral path. As each wedgeshaped bafiie is presented, the flow of material is split into two streams and the streams are recombined as they enter the convergent section after passing the face of the bafiie. The alternate splitting and recombining as the material is gravitated along the continuous spiral path brings about the intimate blending of the particles.

It is to be understood that various modifications may be made of splitting baflies in the divergent portions of the spiral path. For example, provision may be made for lifting and splitting as well as just splitting the stream of material in order to facilitate blending of material differing widely in apparent density. Also within the scope of this invention is a splitting bafile which will split the flow into a plurality of streams.

Spiral path Wall heights of from about one-fourth to one-half the radius of the drum are effective in handling a steady flow of material to produce good blending without spilling the material from one side to the other.

Walls having an inclined angle of about 60 to 90 degrees defining the convergent and divergent portions and channel widths between the wedge-shaped bafiie and the divergent section walls of about one-fourth to one-third the width of the exit throat provide split flow paths which produce homogeneous blending with a minimum of and simplified method and apparatus for effecting a continuous blending of materials which, because of the physical characteristics, are difiicult to blend homogeneously in conventional types of blenders and mixers. Consequently, this invention permits blending such materials in a continuous and efiicient manner with a substant-ial reduction in the rate of attrition normally occurring in conventional types of blending equipment.

The apparatus of this invention can readily be incor porated into a continuous process system, whereas conventional types of blenders operate as batch units. The apparatus of this invention has the advantage of blending powdered or granular material with a minimum of breakage and produces a blend homogeneous throughout without Stratification of like particles.

While the novel features of the invention have been shown and described and are pointed out in the annexed claims, it is to be understood that various omissions, substitutions and changes in construction and arrangement of the parts shown and described may be made by those skilled in the art without departing from the spirit of the invention. Therefore, it is understood that all matters shown or described are to be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An apparatus for continuously blending powdered or granular material varying in particle size and apparent density comprising a rotary drum, means defining a continuous spiral path located around .the inner surface of said drum for conveying said material through said drum along a path that is spiral with respect to said drum, and means located in said spiral path for splittingsaid material into a plurality of streams and for then recombining them ata plurality of points along said spiral path.

2. An apparatus for continuously blending powdered or granular material varying in particle size and apparent density comprising a rotating drum; an inwardly extending wall around the inner surface of said drum, said wall having alternate portions positioned at reversed angularity with respect to each other to define a spiral path having a plurality of alternately convergent and divergent sections; and means located in said divergent sections for dividing each said divergent section into a plurality of channels.

3. An apparatus as claimed in claim 2 in which the dividing means is a wedge-shaped bafiie located in the divergent portion of said spiral path for dividing the divergent section into two channels. a

References Cited in the file of this patent UNITED STATES PATENTS 570,745 Cleveland Nov. 3, 1896 2,187,601 Glaxner Jan. 16, 1940 2,345,554 Burdett Apr. 4, 19 44 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2,869,837 January 20, 195? John Harlan Pickin E It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below. 1

Column 3 line 43 for "inclined" read me included e Signed and sealed this llth day of August 1959.

Attest:

KARL H... AXLINE Attesting Ofiicer ROBERT C. WATSON Commissioner of Patents 

